Liquid crystal display

ABSTRACT

A liquid crystal display according to an exemplary embodiment of the present system and method includes a first insulation substrate, a thin film transistor disposed on the first insulation substrate, a pixel electrode connected to the thin film transistor, a protrusion disposed on the pixel electrode, a second insulation substrate facing the first insulation substrate, a common electrode disposed on the second insulation substrate, and a liquid crystal layer disposed between the pixel electrode and the common electrode, wherein one pixel includes a thin film transistor formation region where the thin film transistor is disposed and a display area where the pixel electrode is disposed, and the protrusion is disposed to overlay at least a portion of edges of the display area.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patentapplication Ser. No. 14/815,443 filed on Jul. 31, 2015, which claimspriority under 35 USC § 119 to Korean Patent Application No.10-2015-0003670 filed in the Korean Intellectual Property Office on Jan.9, 2015, the entire contents of which are incorporated herein byreference.

BACKGROUND (a) Field

The present disclosure relates to a liquid crystal display.

(b) Description of the Related Art

A liquid crystal display is a flat panel display that is widely usedtoday, and generally includes two display panels in which electric fieldgenerating electrodes, such as a pixel electrode and a common electrode,are disposed, and a liquid crystal layer disposed between the twodisplay panels. An image is displayed by applying a voltage to theelectric field generating electrodes to generate an electric field inthe liquid crystal layer, thereby determining the alignment of theliquid crystal molecules in the liquid crystal layer and controlling thepolarization of incident light by the liquid crystal layer.

The liquid crystal display includes switching elements connected torespective pixel electrodes, a plurality of signal lines including gatelines and data lines, and a driver configured to apply a driving signalto the signal lines. By controlling the state of the switching elementsthrough the gate lines, voltages may be applied to the pixel electrodesthrough the data lines.

The driver includes a gate driver for supplying a gate signal includinga gate-on voltage Von and a gate-off voltage Voff to the gate lines of adisplay panel, a data driver for supplying a data signal to the datalines of the display panel, a signal controller for controlling the datadriver and the gate driver, and the like.

Among liquid crystal displays, a liquid crystal display with avertically aligned mode has proved to be popular because it provides arelatively large contrast ratio and a wide reference viewing angle. In aliquid crystal display with a vertically aligned mode, the major axis ofthe liquid crystal molecules are aligned to be perpendicular to a planarsurface of the display panels when an electric field is not applied.

A method for forming cutouts, such as fine slits, in the fieldgenerating electrode is used to provide the wide viewing angle in theliquid crystal display with a vertically aligned mode. Since the cutoutsand protrusions determine the direction in which the liquid crystalmolecules are tilted (tilt direction), it is possible to increase aviewing angle by appropriately arranging the cutouts and protrusions sothat the liquid crystal molecules are tilted in various directions.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the system and methodand therefore may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY

The present system and method provide a liquid crystal display havingadvantages of minimizing optical loss and suppressing the occurrence oftextures even when the display panels are misaligned with each other dueto their curvature.

An exemplary embodiment of the present system and method provides aliquid crystal display including: a first insulation substrate, a thinfilm transistor disposed on the first insulation substrate, a pixelelectrode connected to the thin film transistor, a protrusion disposedon the pixel electrode, a second insulation substrate facing the firstinsulation substrate, a common electrode disposed on the secondinsulation substrate, and a liquid crystal layer disposed between thepixel electrode and the common electrode, wherein one pixel includes athin film transistor formation region where the thin film transistor isdisposed and a display area where the pixel electrode is disposed, andthe protrusion is disposed to overlay at least a portion of edges of thedisplay area.

The pixel electrode may include a plurality of cross-shaped stems, andfine branches obliquely extending from the cross-shaped stems. Thedisplay area may comprise a plurality of sub-regions identified by thecross-shaped stems.

The protrusion may overlay at least a portion of edges of thesub-regions.

The protrusion may include an opening disposed at corners of the edges.

The protrusion may include an opening disposed at sides of the edges.

The pixel electrode may further include a plate part disposed as thecenter of the cross-shaped stem.

The plate part may have a diamond shape.

The liquid crystal display may further include a column spacer disposedon the pixel electrode. The column spacer and the protrusion may bedisposed in the same layer and are made of the same material.

The protrusion may have a height lower than a height of the liquidcrystal layer.

The common electrode may have a plate shape.

The liquid crystal display may further include alignment layers disposedon the pixel electrode and the common electrode, and the alignmentlayers disposed on the pixel electrode may further include reactivemesogen (RM).

The liquid crystal layer may exclude reactive mesogen (RM).

The liquid crystal display may have a curved shape.

As described above, according to the above-described liquid crystaldisplay, it is possible to minimize optical loss and suppress occurrenceof textures even when a display panel is curved and thus upper and lowerpanels are misaligned with each other.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a display device according to anexemplary embodiment of the present system and method.

FIG. 2 is a schematic diagram of two adjacent pixels according to anexemplary embodiment of the present system and method.

FIG. 3 is a layout view illustrating a pixel electrode according to anexemplary embodiment of the present system and method.

FIG. 4 is a layout view of two adjacent pixels of a liquid crystaldisplay according to an exemplary embodiment of the present system andmethod.

FIGS. 5, 6 and 7 are layout views of two adjacent pixels of a liquidcrystal display according to another exemplary embodiment of the presentsystem and method.

FIG. 8 is a liquid crystal molecule alignment image of a portion of onepixel according to an exemplary embodiment of the present system andmethod.

FIGS. 9, 10 and 11 are liquid crystal molecule alignment images of aportion of one pixel according to various exemplary embodiments of thepresent system and method.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present system and method are described more fully hereinafter withreference to the accompanying drawings in which exemplary embodiments ofthe present system and method are shown. Those of ordinary skill in theart would realize that the described embodiments may be modified invarious different ways without departing from the spirit or scope of thepresent system and method.

In the drawings, the thickness of layers, films, panels, regions, etc.,are exaggerated for clarity. Like reference numerals designate likeelements throughout the specification. When an element such as a layer,film, region, or substrate is referred to as being “on” another element,it may be directly on the other element, or intervening elements mayalso be present. In contrast, when an element is referred to as being“directly on” another element, there are no intervening elementspresent.

Hereinafter, a display device according to an exemplary embodiment isdescribed in detail with reference to FIG. 1 .

FIG. 1 is a block diagram illustrating a display device according to anexemplary embodiment of the present system and method.

As shown in FIG. 1 , the display device includes a display panel 300configured to display an image, a data driver 500 configured to drivethe display panel 300, a gate driver 400, and a signal controller 600configured to control the data driver 500 and the gate driver 400.

The display panel 300 includes a plurality of gate lines G1 to Gn and aplurality of data lines D1 to Dm+1. The plurality of gate lines G1 to Gnextend in a horizontal direction, and the plurality of data lines D1 toDm+1, which are insulated from the plurality of gate lines G1 to Gn,extend in a vertical direction to intersect with the plurality of gatelines G1 to Gn. Also, reference voltage lines V1 to Vm that extend in avertical line are disposed between the plurality of data lines D1 toDm+1. The reference voltage lines V1 to Vm are insulated from andintersect with the gate lines G1 to Gn.

Each pixel of a plurality of pixels PX is connected to a correspondingone of the gate lines and a corresponding one of the data lines. Thepixels PX are arranged in a matrix form and formed to extend lengthwisein the horizontal direction, which is also the extending direction ofthe gate lines G1 to Gn. Each pixel PX may include a thin filmtransistor, a liquid crystal capacitor, and a storage capacitor. Acontrol terminal of the thin film transistor may be connected to one ofthe gate lines G1 to Gn, an input terminal of the thin film transistormay be connected to one of the data lines D1 to Dm+1, and an outputterminal of the thin film transistor may be connected to one terminal(pixel electrode) of the liquid crystal capacitor and one terminal ofthe storage capacitor. The other terminal of the liquid crystalcapacitor may be connected to a common electrode and the other terminalof the storage capacitor may receive a storage voltage Vcst. In someexemplary embodiments, a channel layer of the thin film transistor maybe amorphous silicon, polysilicon, or an oxide semiconductor. Thereference voltage lines V1 to Vm provide reference voltages to thepixels PX. The reference voltage has a voltage level that does not varywith time. However, in some exemplary embodiments, the reference voltagemay have a voltage level that varies with time.

As the exemplary liquid crystal display device of the FIG. 1 shows, onedata line is alternately connected to pixels PX disposed to the rightand the left of the data line. For example, when the data line isconnected to a pixel PX disposed to its right in a first row, the dataline is connected to a pixel PX disposed to its left in a second row,and is again connected to a pixel disposed to its right in a third row.On the other hand, one gate line is connected to all the pixels PX ofone row.

In such a structure, an odd pixel and an even pixel, both belonging toone pixel column, are connected to different data lines. Thus, even whenthe data lines D1 to Dm+1 apply data voltages having the same polarityduring one frame, a polarity reversal appearing in a pixel (PX) isrepresented as a dot reversal.

The number of the data lines D1 to Dm+1 may be one more than the number(m) of pixel columns. In the embodiment of FIG. 1 , there is no pixelcolumn on the left of a first data line D1, and therefore, the firstdata line D1 may be alternately connected to the pixel column disposedon the right thereof. There is no pixel column on the right of an(m+1)-th data line Dm+1, and therefore, the (m+1)-th data line Dm+1 maybe alternately connected to the pixel column disposed on the leftthereof.

The signal controller 600 processes input data and control signals thatare input from the outside, so as to make them suitable for theoperating conditions of the liquid crystal panel 300, in response to,for example, a vertical synchronization signal Vsync, a horizontalsynchronizing signal Hsync, a main clock signal MCLK, a data enablesignal DE or the like. Thereafter, the signal controller 600 generatesand outputs image data DAT, a gate control signal CONT1, a data controlsignal CONT2, and a clock signal.

The gate control signal CONT1 may include a scanning start signal STVthat indicates the start of outputting of a gate-on voltage Von, a gateclock signal CPV that controls the output timing of the gate-on voltageVon, and the like.

The data control signal CONT2 may include a horizontal synchronizationstart signal STH that indicates the start of inputting of image dataDAT, a load signal TP that instructs application of the data voltages tothe data lines D1 to Dm+1.

The plurality of gate lines G1 to Gn of the display panel 300 isconnected to the gate driver 400, and the gate driver 400 sequentiallyreceives the gate-on voltage Von according to the gate control signalCONT1 applied from the signal controller 600. A gate-off voltage Voff isapplied to the gate lines G1 to Gn during a period in which the gate-onvoltage Von is not applied.

The plurality of data lines D1 to Dm+1 of the display panel 300 isconnected to the data driver 500, and the data driver 500 receives thedata control signal CONT2 and the image data DAT from the signalcontroller 600. The data driver 500 converts the image data DAT intodata voltages by using gray voltages generated by a gray voltagegenerator (not shown) and transfers the data voltages to the data linesD1 to Dm+1. The data voltages include a positive-polarity data voltageand a negative-polarity data voltage. The positive-polarity data voltageand the negative-polarity data voltage are alternately applied based onframes, columns, or rows and are used for inversion driving. Suchinversion driving is applied to either or both of the case in which amoving image is displayed and the case in which a still image isdisplayed.

In some exemplary embodiments, there may be provided various pixelconnection structures that are not shown in FIG. 1 .

A structure of two adjacent pixels PX is schematically described belowwith reference to FIG. 2 .

FIG. 2 is a schematic diagram of two adjacent pixels according to anexemplary embodiment of the present system and method.

The pixel PX according to an exemplary embodiment of the present systemand method is a horizontal pixel that is formed to extend in ahorizontal direction. Also, the pixel PX mainly includes a thin filmtransistor formation region TA and a display area DA. A pixel electrodeis disposed in the display area DA where an image is displayed throughthe liquid crystal molecules. An element, such as a thin film transistorthat transfers a voltage to be applied to the pixel electrode in thedisplay area DA, and wirings are formed in the thin film transistorformation region TA.

As FIG. 2 shows, a reference voltage line V is disposed in a verticaldirection along the center of the display area DA. Also, each of the twoadjacent pixels PX1 and PX2 includes a first subpixel area PXa and asecond subpixel area PXb that are arranged in two rows.

Each of the first subpixel area PXa and the second subpixel area PXbincludes six sub-regions. The sub-regions are separate from each otherby dotted lines in FIG. 2 . That is, each of the two pixels PX1 and PX2includes 12 sub-regions in total. Also, the reference voltage line V isdisposed to divide the 12 sub-regions into two sets of 6 sub-regions.That is, the reference voltage line V is disposed to traverse the centerof the first subpixel area PXa and the second subpixel area PXb.

Each of the sub-regions includes one cross-shaped stem, based on whichthe sub regions are identified. Although each of the pixels shown in theexemplary embodiment of FIG. 2 is described as including 12 sub-regions,the present system and method are not limited thereto. Any number ofsub-regions is possible.

Also, each of the first subpixel area PXa and the second subpixel areaPXb includes six unit electrodes UP corresponding to the sixsub-regions. The area of a unit electrode UP in the second subpixel areaPXb may be equal to or larger than the area of a unit electrode in thefirst subpixel area PXa. Also, a voltage applied to the second subpixelarea PXb may be lower than a voltage applied to the first subpixel areaPXa.

Also, the gate line 121 extends between the two adjacent pixels PX1 andPX2 in the horizontal direction. Specifically, the gate line 121 extendsbetween the second subpixel area PXb of pixel PX1 and the first subpixelarea PXa of adjacent pixel PX2 in the horizontal direction.

A structure of a pixel electrode and a reference voltage line V in apixel PX according to an exemplary embodiment of the present system andmethod is described below with reference to FIG. 3 .

FIG. 3 is a layout view illustrating a pixel electrode according to anexemplary embodiment of the present system and method.

A pixel electrode disposed in one pixel PX includes a first subpixelelectrode 191 a disposed in the first subpixel area PXa and a secondsubpixel electrode 191 b disposed in the second subpixel area PXb.

Each of the first subpixel electrode 191 a and the second subpixelelectrode 191 b includes six unit pixel electrodes UP corresponding tosix sub-regions. Each of the unit pixel electrodes UP includes across-shaped stem 198 and a plurality of fine branches 199 obliquelyextending from the cross-shaped stem 198. The plurality of fine branches199 may be formed at an angle of 45 degrees, an angle equal to or largerthan 40 degrees, or an angle equal to or smaller than 50 degrees withrespect to the horizontal direction or the vertical direction.

The six unit pixel electrodes UP of the first subpixel electrode 191 aare connected to each other through an extension part. Likewise, the sixunit pixel electrodes UP of the second subpixel electrode 191 b areconnected to each other through an extension part. In the exemplaryembodiment of FIG. 3 , the cross-shaped stems 198 are formed to be incontact with sides of a region where the unit pixel electrodes areformed.

The extension part of the unit pixel electrodes UP may extend from thecross-shaped stem 198. The six pixel electrodes UP that are connected bythe extension part receive the same voltage. While the unit pixelelectrodes of the same subpixel electrode are connected to one anotherthrough the extension part, unit pixel electrodes of different subpixelelectrodes are separate from and not connected to each other.

An upper common electrode of one sub-region where the unit pixelelectrodes UP are disposed is formed to have a plate shape, which is aplane shape that does not include an opening region.

The reference voltage line V is disposed to traverse the center of thefirst subpixel electrode 191 a and the second subpixel electrode 191 b.

An overall structure of a pixel having a pixel electrode, a commonelectrode, and a reference voltage line is described with reference toFIG. 4 .

FIG. 4 is a diagram showing a detailed structure of the pixel accordingto the exemplary embodiment of FIG. 3 , and shows a layout view of twoadjacent pixels of a liquid crystal display according to an exemplaryembodiment of the present system and method.

Referring to FIG. 4 , the liquid crystal display according to anexemplary embodiment of the present system and method includes a lowerdisplay panel and an upper display panel that face each other, and aliquid crystal layer disposed between the two panels.

First, as to the lower panel, a plurality of gate lines 121 is disposedon the lower panel.

The gate lines 121 extend among a plurality of pixel electrodes 191 inthe horizontal direction, and include a first gate electrode 124 a, asecond gate electrode 124 b, and a third gate electrode 124 c thatprotrude upward (orientation as shown in FIG. 4 ) and extend from thegate lines 121. The first gate electrode 124 a, the second gateelectrode 124 b, and the third gate electrode 124 c are formed such thatthe third gate electrode 124 c extends upward from the gate lines 121and then expands, and the first gate electrode 124 a and the secondelectrode 124 b extend again from the third gate electrode 124 c. Thefirst gate electrode 124 a and the second gate electrode 124 may beformed in one expanded region. Also, the gate lines 121 may include abent portion that is bent from a main line extending in a substantiallyhorizontal direction at periodic intervals.

A gate insulating layer is disposed on the gate lines 121. A firstsemiconductor 154 a, a second semiconductor 154 b, and a thirdsemiconductor 154 c are disposed respectively on the first gateelectrode 124 a, the second gate electrode 124 b, and the third gateelectrode 124 c.

A data conductor including a data line 171, a first drain electrode 175a, a second drain electrode 175 b, a third source electrode 173 c, athird drain electrode 175 c, and a reference voltage line 178 isdisposed on the first semiconductor 154 a, the second semiconductor 154b, and the third semiconductor 154 c, and the gate insulating layer.

The data line 171 transfers a data voltage, substantially extends in thevertical direction on a lower substrate, and intersects with the gatelines 121. The data line 171 includes a source electrode 173 a and asecond source electrode 173 b that respectively extend toward the firstand second gate electrodes 124 a and 124 b.

The reference voltage line 178 may include a main line 178 asubstantially parallel to the data line 171 and a branch portion 178 bextending from the main line 178 a and substantially parallel to thegate lines 121. The branch portion 178 b extends to the thin filmformation region TA along the edges of the display area, and one end ofthe branch 178 b forms the third drain electrode 175 c.

The first drain electrode 175 a faces the first source electrode 173 a,the second drain electrode 175 b faces the second source electrode 173b, and the third drain electrode 175 c faces the third source electrode173 c. The third source electrode 173 c is connected to the second drainelectrode 175 b.

The first gate electrode 124 a, the first source electrode 173 a, thefirst drain electrode 175 a, and the first semiconductor 154 a togetherform a first thin film transistor. The second gate electrode 124 b, thesecond source electrode 173 b, the second drain electrode 175 b, and thesecond semiconductor 154 b together form a second thin film transistor.The third gate electrode 124 c, the third source electrode 173 c, thethird drain electrode 175 c, and the third semiconductor 154 c togetherform a third thin film transistor. That is, the first thin filmtransistor and the second thin film transistor receive a data voltagethrough their source electrodes, whereas the third thin film transistorreceives a reference voltage through its source electrode.

A passivation layer is disposed on the data conductor, and a pixelelectrode 191 is disposed on the passivation layer.

Each pixel electrode includes a first subpixel electrode 191 a and asecond subpixel electrode 191 b as described with reference to FIG. 3 .

The first drain electrode 175 a of the first thin film transistor isconnected to the first subpixel electrode 191 a through a first contacthole 185 a.

The second drain electrode 175 b of the second thin film transistor isconnected to the second subpixel electrode 191 b through a secondcontact hole 185 b.

A protrusion 260 is disposed on the subpixel electrodes 191 a and 191 b.The protrusion 160 may be disposed along the edges of the display area,which are the edges of the subpixel electrodes 191 a and 191 b, or maybe disposed along the edges of the unit electrodes UP in one pixel.

The height of the protrusion 260 according to an exemplary embodiment ofthe present system and method may be formed to be lower than the heightof the liquid crystal layer disposed between the upper panel and thelower panel.

The protrusion 260 formed along the edges of the display area and theunit electrodes controls the alignment of the liquid crystal moleculesdisposed in the display area and the unit electrodes, thereby providingimproved controllability liquid crystal over the liquid crystalmolecules. In particular, the protrusion 260 makes it possible to alignthe liquid crystal molecules in the same direction as the liquid crystalmolecules aligned by the fine branches 199.

Although the protrusion is shown as overlapping the edges of the displayarea and the reference voltage line in the exemplary embodiment of FIG.4 , the present system and method are not limited thereto, and theprotrusion may be selectively formed at the edges of unit electrodes.

In some exemplary embodiments, a column spacer (not shown) may bedisposed on the pixel electrodes 191 a and 191 b. The column spacer maymaintain a gap between the upper panel and the lower panel according toa height. The column spacer may be formed of the same material andthrough the same process as the protrusion 260. Therefore, the columnspacer and the protrusion may be disposed in the same layer.

Next, a color filter and a light blocking member may be disposed on theupper panel (not shown).

The light blocking member may be called a black matrix, and may blocklight leakage between the pixel electrodes 191. The light blockingmember may cover most of the data line 171, the gate lines 121, and thethin film transistors.

The color filter may display one of several primary colors, such asthree primary colors of red, green, and blue. According to anotherexemplary embodiment of the present system and method, at least one ofthe light blocking member and the color filter may be disposed in thelower panel.

An overcoat is disposed on the color filter and the light blockingmember, and an upper common electrode is disposed on the overcoat. Theupper common electrode, which receives a common voltage Vcom, may beformed to have a plate shape as described with reference to FIG. 3 .

The liquid crystal layer disposed between the lower panel and the upperpanel includes liquid crystal molecules having negative dielectricanisotropy. That is, the liquid crystal molecules may be aligned suchthat a main axis thereof is substantially perpendicular to surfaces ofthe two panels when an electric field is not being applied. The liquidcrystal layer may not include reactive mesogen (RM).

Although not shown, the liquid crystal display according to an exemplaryembodiment of the present system and method includes a first alignmentlayer and a second alignment layer disposed on the pixel electrode andthe common electrode. In this case, the first alignment layer and thesecond alignment layer may be different from each other. As an example,the alignment layer disposed on the pixel electrode may further includereactive mesogen (RM).

Although the color filter and the light blocking member are describedabove as being disposed in the upper panel, the present system andmethod are not limited thereto, and one of the color filter and thelight blocking member may be disposed in the lower panel, or both of thecolor filter and the light blocking member may be disposed in the lowerpanel.

The liquid crystal display according to an exemplary embodiment of thepresent system and method may have a curved shape, and as a result, theupper and lower panels may be misaligned with each other. According toexemplary embodiments of the present system and method, the commonelectrode disposed on the upper panel is formed to have a plate shapeand the protrusion, which assists the alignment of the liquid crystalmolecules, is disposed in the lower panel. In this manner, the alignmentof the liquid crystal molecules is easily controlled despite themisalignment. Therefore, exemplary embodiments of the present system andmethod make it possible to suppress texture generation and provide adisplay device having improved display quality.

Hereinafter, other embodiments of the present system and method aredescribed with reference to FIGS. 5 to 7 . FIGS. 5 to 7 are layout viewsof two adjacent pixels of a liquid crystal display according to otherexemplary embodiments of the present system and method. The liquidcrystal display according to the exemplary embodiments of FIGS. 5 and 6is identical to the above-described exemplary embodiment of FIG. 4except for the shape and arrangement of the protrusion. The liquidcrystal display according to the embodiment of FIG. 7 differs from thatof FIG. 4 in the structure of the subpixel electrodes 191 a and 192 b.To avoid redundancy of description, the description of the same orsimilar elements is omitted.

First, referring to FIG. 5 , a protrusion 260 is disposed on subpixelelectrodes 191 a and 191 b. The protrusion 260 may be disposed along theedges of the display area, which are the edges of the subpixelelectrodes 191 a and 191 b, or may be disposed along the edges of theunit electrodes UP in one pixel.

The protrusion 260 according to another exemplary embodiment of thepresent system and method may include openings disposed at its corners.Specifically, the protrusion 260 formed along the edges of the displayarea or the unit electrodes may have a rectangular plane shape and maybe formed such that portions of the protrusion 260 at the corners areremoved or not formed in the rectangular shape. This protrusionstructure allows the liquid crystal molecules to easily move through theopenings during a process of manufacturing the liquid crystal display.

The height of the protrusion 260 according to an exemplary embodiment ofthe present system may be formed to be lower than the height of theliquid crystal layer disposed between the upper panel and the secondpanel.

The protrusion 260 formed along the edges of the display area and theunit electrodes controls the alignment of the liquid crystal moleculesdisposed in the display area and the unit electrodes, thereby providingimproved controllability over the liquid crystal molecules. Inparticular, the protrusion makes it possible to align the liquid crystalmolecules in the same direction as the liquid crystal molecules alignedby the fine branches 199.

Although the protrusion is shown as overlapping the edges of the displayarea and the reference voltage line in the exemplary embodiment, thepresent system and method are not limited thereto, and the protrusionmay be selectively formed at the edges of unit electrodes.

Referring to FIG. 6 , unlike the exemplary embodiment of FIG. 5 , theprotrusion 260 may include openings disposed at its edges instead of itscorners.

The protrusion 260 is formed along the edges of the display area or thesub-regions and may have a rectangular plane shape. In this case,portions of the sides of the rectangular plane shape may be removed ornot formed so as to be opened. The openings make movement of the liquidcrystal molecules easy during the process of manufacturing the liquidcrystal display, while the protrusion 260 is still able to assist incontrolling the alignment of the liquid crystal molecules.

Referring to FIG. 7 , the pixel electrode 191 may include a firstsubpixel electrode 191 a and a second subpixel electrode 191 b that aredisposed within one pixel PX.

Each of the first subpixel electrode 191 a and the second subpixelelectrode 191 b includes six unit pixel electrodes UP corresponding tosix sub-regions. Each of the unit pixel electrodes UP includes a platepart 197 and a plurality of fine branches 199 extending outward from thesides of the plate part 197. The plurality of fine branches 199 may beformed at an angle of 45 degrees with respect to the horizontaldirection or the vertical direction or may be formed at an angle equalto or larger than 40 degrees or an angle equal to or smaller than 50degrees. Also, the fine branches 199 may extend perpendicularly from thesides of the plate part 197. Controllability of the liquid crystalmolecules is enhanced through fringe fields generated at the sides ofthe edges of the plate part 197, thereby further increasing thetransmittance of the liquid crystal display.

The six unit pixel electrodes of the first subpixel electrode 191 a areconnected to each other through an extension part. Similarly, the sixunit pixel electrodes of the second subpixel electrode 191 b areconnected to each other through an extension part. Although the platepart 197 is illustrated as having a size in which the plate part 197 isin contact with the sides of a region where the unit pixel electrodesare formed, the plate part 197 may be formed to be smaller. In suchcase, the fine branches 199 may also be disposed at the corners of theplate part 197. The extension part of the unit pixel electrodes UP mayextend from the plate part 197 or may extend from the fine branches 199.The six pixel electrodes UP that are connected by the extension partreceive the same voltage. While the respective unit pixel electrodes ofthe same subpixel electrode are connected to one another through theextension part, unit pixel electrodes of different subpixel electrodesare separate from and not connected to each other.

The common electrode 270 according to another exemplary embodiment ofthe present system and method is formed to have a plate shape and doesnot include a separate pattern or slit.

The reference voltage line 178 is disposed to traverse the center of thefirst subpixel electrode 191 a and the second subpixel electrode 191 b.

A protrusion 260 is disposed on the subpixel electrodes 191 a and 191 b.The protrusion 260 may be disposed along the edges of the display area,which are edges of the subpixel electrodes 191 a and 191 b, or may bedisposed along the edges of the unit electrodes UP in one pixel. Theprotrusion 260 according to the various exemplary embodiments describedabove may be disposed without limitation, for example, in the embodimentof FIG. 7 .

Although the shape of the pixel electrode is specified as illustrated inFIG. 7 , the present system and method are not limited thereto, andvarious shapes of the pixel electrode are possible.

Hereinafter, liquid crystal alignment images according to embodiments ofthe present system and method are described with reference to FIGS. 8 to10 . FIG. 8 is a liquid crystal molecule alignment image of a portion ofone pixel according to an exemplary embodiment of the present system andmethod. FIGS. 9 to 11 are liquid crystal molecule alignment images of aportion of one pixel according to various exemplary embodiment of thepresent system and method.

First, referring to FIG. 8 , the liquid crystal molecule alignment imageof a sub-region shows a cross-shaped stem, a plurality of fine branchesextending therefrom, and a protrusion surrounding the edges of the finebranches, according to an exemplary embodiment.

As can be seen from FIG. 9 , the liquid crystal molecules disposed overthe fine branches are generally aligned in the direction in which thefine branches extend. Moreover, the liquid crystal molecules disposedaround the protrusion are also aligned in the same direction as thoseliquid crystal molecules aligned by the fine branches.

That is, according to an exemplary embodiment of the present system andmethod, although the influence of the fine branches are weaker near theedges of the sub-regions, the protrusion helps to align the liquidcrystal molecules near the edges of the sub-regions in the samedirection as the liquid crystal molecules that are disposed over andaligned by the fine branches.

FIG. 9 is a liquid crystal molecule alignment image when the height ofthe protrusion according to an exemplary embodiment of the presentsystem and method is 0.5 μm. FIG. 10 is a liquid crystal moleculealignment image when the height of the protrusion is 1.0 μm. FIG. 11 isa liquid crystal molecule alignment image when the height of theprotrusion is 1.5 μm.

Referring to FIGS. 9 to 11 , it can be seen that the liquid crystalmolecules are aligned along the extension directions of the finebranches around the cross-shaped stem, and in particular, liquid crystalmolecules disposed around the edges are aligned in the directions of thecross-shaped stem and the fine branches due to the protrusion disposedat the edges of the sub-regions.

That is, as shown in FIGS. 9 to 11 , the liquid crystal moleculesalignment directions due to the protrusion are identical to the liquidcrystal molecules alignment directions due to the fine branches and thecross-shaped stem, and more effective liquid crystal control is possibleat the edges of the sub-regions by means of the protrusion.

As described above, the liquid crystal display according to theexemplary embodiments of the present system and method is capable ofeffectively controlling liquid crystal molecules by means of theprotrusion disposed in the lower panel even in a case in which thecommon electrode disposed in the upper panel is formed in a plate form.Therefore, it is possible to provide a liquid crystal display having animproved display quality.

While the present system and method are described in connection withexemplary embodiments, the present system and method are not limited tothe disclosed embodiments. On the contrary, the present system andmethod cover various modifications and equivalent arrangements includedwithin the spirit and scope of the appended claims.

<Description of symbols> 121: Gate line 124: Gate electrode 154:Semiconductor 171: Data line 173: Source electrode 175: Drain electrode178: Reference voltage line 191: Pixel electrode 198: Cross-shaped stem199: Fine branch 400: Gate driver

What is claimed is:
 1. A liquid crystal display comprising: a firstsubstrate and a second substrate facing each other; a liquid crystallayer disposed between the first substrate and the second substrate; atransistor disposed on the first substrate; a gate line extending in afirst direction; a data line extending in a second direction crossingthe first direction; a pixel electrode electrically connected to thetransistor; and a protrusion disposed on the pixel electrode, theprotrusion protruding toward the liquid crystal layer, wherein the pixelelectrode comprises a plurality of unit electrodes electricallyconnected to each other, each of the unit electrodes comprising across-shaped stem, wherein the protrusion comprises a first portionextending along and overlapping a boundary between adjacent unitelectrodes of the plurality of unit electrodes and no voltage is appliedto the protrusion, wherein the transistor is electrically connected tothe gate line and the data line, wherein the protrusion furthercomprises a second portion extending in the first direction and a thirdportion extending in the second direction, and wherein at least one ofthe second portion or the third portion has an opening.
 2. The liquidcrystal display of claim 1, wherein the opening extends in the firstdirection or the second direction.
 3. The liquid crystal display ofclaim 1, wherein the second portion overlaps the gate line, and thethird portion overlaps the data line.
 4. The liquid crystal display ofclaim 1, wherein a combined perimeter of the second portion and thethird portion forms a substantially rectangular shape in a plan view. 5.The liquid crystal display of claim 1, wherein: the liquid crystaldisplay has a curved shape.
 6. The liquid crystal display of claim 1,wherein an end of the second portion and an end of the third portion areseparated from and oppose each other with the opening therebetween. 7.The liquid crystal display of claim 6, wherein the opening is disposedat a corner of the pixel electrode.
 8. The liquid crystal display ofclaim 1, wherein a length of the pixel electrode in the first directionis different from a length of the pixel electrode in the seconddirection.
 9. The liquid crystal display of claim 8, wherein a length ofthe second portion overlapping one pixel is different from a length ofthe third portion overlapping the one pixel.